Fertility rates and birth outcomes after ChAdOx1 nCoV-19 (AZD1222) vaccination

Despite the absence of supporting evidence for such a risk, low biological plausibility, and preliminary data supporting the safety of mRNA vaccines in pregnancy,1–3 this claim has become widespread, and it has been challenged by WHO.4 Vaccine hesitancy during pregnancy, or among women of childbearing age, could have substantial public health consequences because infection with SARS-CoV-2 during pregnancy is a risk factor for severe maternal illness and complications.5,6 We have analysed pregnancies that have occurred in four ongoing phase 1, phase 2, and phase 3 clinical trials of ChAdOx1 nCoV-19 (AZD1222)7 in three countries (NCT04324606 and NCT04400838 in the UK; NCT04536051 in Brazil; and NCT04444674 in South Africa). [...]termination of pregnancy is illegal in Brazil, and uncertainty remains about whether the reports of early pregnancy losses were all miscarriages. [...]a combined analysis of either miscarriage or termination was done for all sites (table 2), with separate subgroup analyses for termination alone and for miscarriage alone, excluding the Brazilian data. Supplementary Material Supplementary appendix ChAdOx1 nCoV-19 (n=4925) Control (n=4830)* Fertility rate ratio (95% CI) p value Pregnant women (fertility rate)† 50 (0·0102) 43 (0·0089) 1·14 (0·76–1·71) 0·53 Viable pregnancies (fertility rate)‡ 32 (0·0065) 29 (0·0060) 1·08 (0·66–1·79) 0·80 Table 1 Fertility rates ChAdOx1 nCoV-19 (n=72) Control (n=35) Risk ratio (95% CI) p value Miscarriage, excluding Brazilian data 6/43 (14%) 5/24 (21%) 0·67 (0·23–1·97) 0·51 Termination, excluding Brazilian data 8/43 (19%) 6/24 (25%) 0·74 (0·29–1·89 0·55 Miscarriage or termination, all 23/72 (32%) 13/35 (37%) 0·86 (0·50–1·49) 0·67 Preterm birth 3/10 (30%) 0/5 (0%) Not calculable 0·51* Full-term birth 7/72 (10%) 5/35 (14%) 0·68 (0·23–1·99) 0·52 Ongoing pregnancy 39/72 (54%) 17/35 (49%) 1·12 (0·75–1·67) 0·68 Table 2 Pregnancy outcomes